> Hang any old length of off-cut material (steel, copper rod) horizontally > on a couple of strings. When you knock one end of the piece longitudinally with > a hammer, the impulse sends it away from the hammer head. > This appears to be `instantaneous' but there is a delay due to the need > for the impulse to reach the far end of the strike-ee rod, > change phase 180degree and reflect back to the hammer. > Once it gets there, the two metal pieces separate for the first time. > > The time delay can be measured by closing a circuit (hammer / rod) and > monitoring by scope. Voila, speed of sound in metals. Great teaching demo Wonder if a PIC could clock it from contact to rebound. Probably too fast.though. Thanks! Win Wiencke Image Logic Corporation -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu